package localchat import ( "encoding/json" "log" "net" "os" "time" ) type UdpMessage struct { Hostname string `json:"hostname"` Type string `json:"type"` Time time.Time `json:"time"` IP string `json:"ip"` Message any `json:"message"` } type UdpAddress struct { Hostname string `json:"hostname"` IP string `json:"ip"` } var OnlineUsers []UdpAddress func init() { go InitBroadcast() go ListenForBroadcast() } func InitBroadcast() { ticker := time.NewTicker(5 * time.Second) // 每 5 秒发送一次广播消息 defer ticker.Stop() for range ticker.C { hostname, err := os.Hostname() if err != nil { log.Printf("Failed to get hostname: %v", err) continue } message := UdpMessage{ Type: "online", Hostname: hostname, Message: "", } //发送多播消息 broadcastAddr := GetBroadcastAddr() err = SendBroadcast(broadcastAddr, message) if err != nil { log.Println("Failed to send broadcast message:", err) } } } func SendBroadcast(broadcastAddr string, message UdpMessage) error { addr, err := net.ResolveUDPAddr("udp4", broadcastAddr) if err != nil { log.Printf("Failed to resolve UDP address %s: %v", broadcastAddr, err) return err } // 使用本地地址进行连接 localAddr, err := net.ResolveUDPAddr("udp4", "0.0.0.0:0") if err != nil { log.Printf("Failed to resolve local UDP address: %v", err) return err } conn, err := net.ListenUDP("udp4", localAddr) if err != nil { log.Printf("Failed to listen on UDP address %s: %v", broadcastAddr, err) return err } defer conn.Close() data, err := json.Marshal(message) if err != nil { log.Printf("Failed to marshal JSON for %s: %v", broadcastAddr, err) return err } _, err = conn.WriteToUDP(data, addr) if err != nil { log.Printf("Failed to write to UDP address %s: %v", broadcastAddr, err) return err } log.Printf("发送消息到 %s 成功", broadcastAddr) return nil } // ListenForBroadcast 监听多播消息 func ListenForBroadcast() { broadcastAddr := GetBroadcastAddr() addr, err := net.ResolveUDPAddr("udp4", broadcastAddr) if err != nil { log.Fatalf("Failed to resolve UDP address: %v", err) } // 使用 ListenMulticastUDP 创建多播连接 conn, err := net.ListenMulticastUDP("udp4", nil, addr) if err != nil { log.Fatalf("Failed to listen on UDP address: %v", err) } defer conn.Close() // 获取本地 IP 地址 // localIP, err := libs.GetIPAddress() // if err != nil { // log.Printf("Failed to get local IP address: %v", err) // } // 开始监听多播消息 buffer := make([]byte, 1024) for { n, remoteAddr, err := conn.ReadFromUDP(buffer) if err != nil { log.Printf("Error reading from UDP: %v", err) continue } var udpMsg UdpMessage err = json.Unmarshal(buffer[:n], &udpMsg) if err != nil { log.Printf("Error unmarshalling JSON: %v", err) continue } // if udpMsg.IP == localIP { // continue // } // 从 remoteAddr 获取 IP 地址 ip := remoteAddr.IP.String() if !contains(OnlineUsers, ip) { OnlineUsers = append(OnlineUsers, UdpAddress{Hostname: udpMsg.Hostname, IP: ip}) log.Printf("在线用户: %v", OnlineUsers) } log.Printf("Received message from %s: %s", remoteAddr, udpMsg.Hostname) } } func contains(slice []UdpAddress, element string) bool { for _, v := range slice { if v.IP == element { return true } } return false } func GetOnlineUsers() []UdpAddress { return OnlineUsers } func GetBroadcastAddr() string { return "224.0.0.251:20249" }